This invention relates to methods and apparatus for reducing the amount of digital data required to acceptably represent and reproduce voice signals.
There are many applications in which there is a need for minimizing the amount of data required to acceptably represent voice signals. For example, in ordinary real-time voice transmission systems, reducing the amount of data required to represent the voice signal reduces the bandwidth required to transmit that signal or allows more voice signals to be transmitted in the same bandwidth. Similarly, in systems in which voice signals must be recorded for subsequent playback, reducing the amount of data representing the voice signal reduces the amount of storage or memory required to store a given quantity of voice information or increases the amount of voice information that can be stored in a given amount of memory. Voice processing or voice mail systems are an example of systems in which voice signals must be recorded for subsequent playback and which can benefit from reducing the amount of digital data which must be stored.
Although it is thus desirable in many situations to reduce the amount of data which must be transmitted or stored to represent voice, the quality of the voice transmitted or stored and subsequently reproduced is also frequently very important. In general, the more data that is transmitted or stored, the better the quality of the transmitted or subsequently reproduced voice. Also, although it is desirable to try to reduce cost by reducing the amount of data transmitted or stored, the data compression technique employed should not be so time consuming or computationally complex that increased processing delays or costs erode or offset the advantages of compressing the data.
In view of the foregoing, it is an object of this invention to provide improved and/or simplified methods and apparatus for compressing the digital data required to represent voice.
It is a more particular object of this invention to provide methods and apparatus for compressing voice data, which methods and apparatus effect a good compromise between minimizing the amount of data required to represent the voice signal, on the one hand, and providing high quality voice transmission or reproduction, on the other hand.
It is another more particular object of this invention to provide methods and apparatus for compressing voice data, which methods and apparatus effect a good compromise between minimizing the amount of data required to represent the voice data, on the one hand, and avoiding unduly complex and/or time consuming data compression techniques, on the other hand.